Method of loading tendons into the knee

ABSTRACT

A surgical method for loading ligament grafts into a joint. A longitudinal-socket formed in a bone is intersected by a transverse pin. A flexible strand is drawn with the pin through the bone. A looped portion of the strand is diverted so as to protrude out of the entrance to the longitudinal socket. The ends of the strand remaining accessible on either side of the bone. The ligament graft is captured within the strand loop protruding from the entrance to the socket. The strand is retracted into the socket, drawing the graft into the socket by pulling on the accessible ends of the flexible strand. The graft is fixed in the socket using a transverse implant.

This application is a continuationof U.S. application Ser. No.09/346,709, filed Jul. 2, 1999 now U.S. Pat. No. 6,132,433, which is acontinuation of U.S. application Ser. No. 9/015,618, filed Jan. 29,1998, now U.S. Pat. No. 5,918,604, claims the benefit of U.S.Provisional Application is a continuation of U.S. application Ser. No.09/346,709, filed Jul. 2, 1999, now U.S. Pat. No. 6,132,433, which is acontinuation of U.S. application Ser. No. 09/015,618, filed Jan. 29,1998, now U.S. Pat. No. 5,918,604, and U.S. Ser. No. 60/037,610, filedFeb. 12, 1997.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to reconstruction of the anterior cruciateligament (ACL), and, more specifically, to surgical graft fixation usingsemitendinosus and gracilis tendon autografts.

2. Description of the Related Art

When a ligament or tendon becomes detached from associated bone, surgeryusually is required to re-secure the ligament or tendon. Often, asubstitute ligament, or graft, is attached to the bone to facilitatere-growth and permanent attachment. Various methods of ligament graftattachment are known, including staples, suture over buttons, andinterference screw fixation.

Various problems exist with the known fixation methods. Staples andsuture buttons are disadvantageous because they often do not providefixation sufficient to withstand the normal tensile loads. With suturebutton fixation, for example, a strand of suture couples the button andthe substitute ligament. This strand becomes the “weakest link in thechain,” and if the strand breaks, the ligament detaches.

A stronger graft attachment can be obtained by interference screwfixation, whereby an interference screw is used to wedge a graft boneblock to the wall of a graft tunnel. See, e.g., U.S. Pat. Nos.5,211,647, and 5,603,716, incorporated herein by reference.

Although interference screw attachment is more secure than using staplesor suture buttons, it is sometimes neither possible nor desirable toprovide such fixation, particularly in the femoral tunnel. In revisionsituations, for example, where a previous reconstruction has beenperformed, placing a second femoral tunnel placed close to the previoustunnel may not be indicated.

In other cases, a semitendinosus graft must be used because the previousreconstruction used the mid third patellar tendon. Although abone-semitendinosus graft-bone construct may be prepared using aworkstation as disclosed in U.S. Pat. No. 5,397,357, such a procedure istime consuming, and may be undesirable for other reasons.

A fixation technique which provides strong attachment of asemitendinosus graft in the femoral tunnel, using a transverse implant,is disclosed in U.S. Pat. No. 5,601,562, of common assignment with thepresent application, and incorporated herein by reference. Thetransverse implant is inserted through a loop in a tendon graft. Athreaded portion of the implant screws into the bone as the implant isadvanced with rotation into the repair site. The technique isdisadvantageous, however, because the graft can become wrapped aroundthe implant as it is rotated. An improved bone implant is the subject ofa co-pending U.S. patent application, attorney docket no. P/1493-155.

In addition, the prior art technique noted above requires a forkedinsertion tool, and a large femoral tunnel is needed to accommodate theforked insertion tool. As a result, the large femoral tunnel undesirablyallows the graft to slide laterally, or “wipe” back and forth, along thefixation implant. Moreover, the diameter of the implant necessarily islimited by the size of the opening in the forked insertion tool.

As a further disadvantage, the technique also requires the extra stepsof forming and wedging a bone plug into the femoral tunnel afterinsertion of the ligament. Moreover, the technique does not accommodatea closed-loop graft construct, since the graft must have a free end inorder to be inserted with the forked insertion tool. Further, thetechnique may not be indicated in revision procedures.

Various endoscopic techniques and instruments relating to graft fixationare known in the prior art and can be used in the practice of thepresent invention. U.S. Pat. No. 5,320,636 to Schmieding discusses anendoscopic drill guide for graft tunnel location. U.S. Pat. No. Des.378,780 illustrates a cannulated headed reamer as can be used in femoralsocket formation. U.S. Pat. Nos. 5,269,786 and 5,350,383 disclose drillguides for location of bone tunnels.

The need exists for fixation techniques that utilize narrowerfemoral/tibial tunnels, to prevent wiping, and that do not require theinsertion of bone plugs. Also, the need exists for graft ligamentloading techniques that can accommodate closed-looped grafts, that donot require specialized insertion tools to load the graft into the-knee,and that can be indicated in certain revision procedures.

SUMMARY OF THE INVENTION

The present invention overcomes the problems of the prior art andfulfills needs such as those noted above by providing a surgical methodfor loading tendon grafts into a joint and fixating the grafts using atransverse, intraosseous implant. The inventive technique advantageouslyuses narrow tibial and femoral tunnels, and eliminates the use ofsutures, tapes, or extra-osseous metal fixation devices. The procedurealso is indicated for revisions that would otherwise be jeopardized bysecondary femoral tunnel creation. In addition, the technique can beimplemented using a transverse implant that is advanced by impactioninto the bone.

As applied in the knee, the method includes the use of standardtechniques to drill a longitudinal tunnel in the tibia. Subsequently, afemoral socket is formed, preferably in the lateral femoral condyle.According to the present invention, forming the socket is preferred toforming a tunnel through the lateral femoral cortex. Advantageously, thediameters of the tibial tunnel and femoral socket are made just largeenough to accommodate the graft in a snug fit.

A tunnel hook, mounted on a cross-pin drill guide, is inserted throughthe tibial tunnel and into the femoral socket. A drill pin directed bythe drill guide is drilled through the femur to intersect the femoralsocket. The drill pin passes through the capture slot of the tunnelhook.

A hole then is formed in the femur, preferably using a cannulated drillplaced over the guide pin, to accommodate a threaded section of thetranstibial implant. A channel is formed in the lateral femoral cortexto accommodate the remainder of the implant, preferably using a dilatorplaced over the guide pin.

Next, a flexible strand, preferably a wire formed of nitinol, isattached to the guide pin and pulled through the femur. Equal lengths ofthe strand protrude from the medial and lateral sides of the femoralshaft, and are secured to prevent accidental pull-out. The tunnel hookis withdrawn, the strand being captured in the slot of the hook.

The hook is retracted completely, through the femoral socket and out ofthe tibial tunnel, such that a loop of the flexible strand protrudesfrom the entrance to the tunnel. Free ends of the strand remain exposedon either side of the femoral shaft.

The graft is passed through the diverted loop of the flexible strand.The loop is retracted into the femoral socket by pulling evenly on themedial and lateral ends of the strand. As a result, the graft is drawninto the socket.

The cannulated implant is placed over the wire and driven into thefemur. The implant preferably is formed with back-biting threads.Accordingly, the implant easily can be impact driven into the repairsite, and yet can be removed if necessary by rotation. The cannulatedimplant passes over the strand and under the tendon, thus securing thegraft in the femoral socket.

Tibial fixation of the graft can be performed by various known methods,including interference screw fixation, which provides the most securepost-operative result; distal fixation with a cancellous screw using apost and washer technique; and a belt buckle staple technique utilizinga pair of ligament staples.

An alternative method of tendon loading is also provided for aclosed-loop graft reconstruction. According to the alternative method, aflexible line is joined to one end of the strand. A strand/line loop isformed so as to protrude from the entrance to the tibial tunnel andpresent the junction between the strand and the line. The strand and theline are dejoined, opening the strand/line loop to accept the graft. Thestrand and line are rejoined so as to capture the graft, and theprocedure continues substantially as set forth above.

Other features and advantages of the present invention will becomeapparent from the following description of the invention which refers tothe accompanying drawings. For example, although the description hereinrelates to ACL grafts and forming femoral tunnels in the knee, it willbecome apparent that expanded indications for the inventive methodinclude other joints and replacement of other ligament or tendonstructures using various types of graft constructs.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an elevation of a tunnel hook according to the presentinvention.

FIG. 2 is a distal end view of the tunnel hock of FIG. 1.

FIG. 3 is an elevation of a drill pin according to the presentinvention.

FIG. 4 is an enlarged view of the distal tip of the drill pin of FIG. 3.

FIG. 5 is a distal end view of the drill pin of FIGS. 3 and 4.

FIG. 6 is an elevation of a tunnel dilator according to the presentinvention.

FIG. 7 illustrates a graft-passing wire according to the presentinvention.

FIG. 8 illustrates a transverse implant having back-biting threadsaccording to the present invention.

FIG. 9 is an enlarged detail view of the back-biting threads of thetransverse implant illustrated in FIG. 8.

FIG. 10 is a schematic view of a hook and a drill pin mounted on a drillguide and disposed within the femoral socket according to the presentinvention.

FIG. 11 is a schematic view of a tunnel dilator being used to form afemoral-channel for the transverse implant according to the presentinvention.

FIG. 12 illustrates a flexible strand attached to the drill pin andbeing pulled through the femur according to the present invention.

FIG. 13 illustrates a loop of the flexible strand being pulled by thehook and out through the femoral socket according to the presentinvention.

FIG. 14 illustrates the flexible strand loop having been divertedthrough the tibial tunnel, capturing a ligament graft, and pulling thegraft into the tibial tunnel according to the present invention.

FIG. 15 illustrates the ligament graft, having been loaded through thelongitudinal tibial tunnel and into the femoral socket, being fixatedusing a transverse implant according to the present invention.

FIG. 16 illustrates a completed tendon graft repair including tibialfixation with an interference screw.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring initially to FIGS. 1 and 2, the present invention involves theuse of a slim, longitudinal tunnel hook 2, which includes a shaft havinga distal end and a proximal end. The distal end of tunnel hook 2 isprovided with a hook 4, having a capture slot 6.

Various features of tunnel hook 2 are provided for ease of use in theinventive procedure of the present invention. The purpose of thefollowing features will become more clear in light of the methoddescribed below. Angled opening 8 allows escape of a graft-passing wirefrom capture slot 6. Channels 10 on either side of hook 4 accommodateportions of the graft-passing wire as it forms a loop through a femoraltunnel. The proximal end of tunnel hook 2 features a mounting flange 11for engagement with a drill guide.

Referring to FIGS. 3, 4, and 5, the invention also involves the use of adrill pin 12, which includes an elongated, narrow shaft having a pointeddistal end and a proximal end. The distal end of drill pin 12 isprovided with a sharp, trocar tip 14 and a fluted drilling region 16disposed adjacent to and proximal the faces of trocar tip 14. Theproximal end of drill pin 12 includes a hook 18 having an angled openinginto its capture slot for engaging the graft-passing wire, as describedmore fully below.

Referring to FIG. 6, a tunnel dilator 20 is shown. Tunnel dilator 20 hasa tapered distal end and a proximal end. Dilator 20 is cannulated to bereceived over drill pin 12. The dilator has an initial taper 22 at thedistal end for insertion into the bone where the drill pin enters. Acylindrical portion 24 forms a channel in the femur for receiving animplant shaft. An interim fluted portion 26 can be providedalternatively to form a hole for receiving threads of the implant, asdescribed below. A depth stop 28 is formed proximally.

Referring to FIG. 7, a nitinol graft-passing wire 30 is shown. Passingwire 30 includes a flexible portion 32 having a loop 34 formed on thedistal end and a rounded proximal end 36.

FIGS. 8 and 9 illustrate a transverse implant 40. Implant 40 has athreaded proximal end and a threaded distal ends. The implant iscannulated to be received over graft-passing wire 30. The implant has ataper 42 formed toward the distal end. The proximal end includesback-biting, helical threads 44 and a drive socket 46. As shown indetail in FIG. 9, threads 44 have a sloping distal face 48 and aproximal face 50 meeting at a radiused edge 52. Distal face 48 forms anangle A of about 72° with a perpendicular to the central axis of theimplant. Proximal face 50 forms an angle B of about 18° with theperpendicular. The implant can be driven by impaction into bone, andthen, if necessary, can be subsequently removed by screw rotation asdiscussed below.

The method of the present invention is described with reference to FIGS.10 through 16. A longitudinal tibial tunnel 56 is formed using knowntechniques of drilling up through the tibia 58. Reproducible tunnelplacement is achieved using instruments that reference intra-articularanatomical constants. A cannulated drill, received over a guide, is usedto drill the tibial tunnel. Depending on the size of the graft, tunneldiameters of 7, 8, 9, and 10 mm are can be used.

Once the tibial tunnel is formed, a cannulated headed reamer is used toform a closed-ended socket 60 in the femur 62. The socket is formed to aminimum depth of about 40 mm to accommodate the insertion depth oftunnel hook 2. The knee should be placed in 90° of flexion when formingthe tibial tunnel and femoral socket.

The tunnel and socket can be modified in various ways using tunnel taps.For example, crenulations formed in the tibial tunnel provide additionalfriction and helps eliminate unwanted graft rotation during interferencescrew insertion. A spiral groove formed in the tunnel wall providesadditional interference friction of the graft collagen against thecompressed cancellous bone in the tunnel. A rasp may be used to createan oval-shaped tunnel and femoral socket to accommodate insertion offour tendon strands.

After the tibial tunnel and femoral socket are complete, tunnel hook 2,fitted onto a C-ring cross-pin drill guide 64, is inserted throughtibial tunnel 56 and into femoral socket 60. Tunnel hook 2 will capturewithin slot 6 the graft-passing wire 12 used in loading the grafttendons into the femoral socket, as described below with respect toFIGS. 12 and 13.

Referring again to FIG. 10, with tunnel hook 2 and drill guide 64 inplace, a 2 mm drill pin sleeve 66 is advanced in the direction of arrowA up to the skin proximal to the femoral condyle to indicate an incisionsite. The drill guide is positioned to allow the pin to pass parallel tothe coronal plane, without excessive posterior or anterior divergence. A2-cm incision is made transversely at this site through the skin andfascia lata, and soft tissue is cleared down to the condyle. Drill pinsleeve 66 is advanced until it contacts bone. Over-tightening of thedrill pin sleeve against the femoral cortex is avoided to prevent thedrill pin from deviating and-missing capture slot 6 of tunnel hook 2. Adepth indicator on the sleeve is used to gauge the length of implant 40that will be required.

With the sleeve in position against the cortical bone, drill pin 12, 2mm in diameter, is chucked into a power drill 68, and advanced withrotation through the femur until it exits the skin on the medial side70. To ensure that the drill pin passes within the capture slot 6 oftunnel hook 2, torque on the drill guide and changes in knee flexion areavoided during drilling.

Referring to FIG. 11, a cannulated drill is placed over the guide pin todrill a hole 71 to accommodate threaded section 44 of implant 40. Thedrill is replaced with tunnel dilator 20, which is used to form achannel in the femur for the remainder of implant 40. Tunnel dilator 20is mounted onto a driver/extractor 72 and driven with a mallet in thedirection of arrow B up to the depth stop.

Referring to FIG. 12, once the channel has been formed, loop 34 ofnitinol graft-passing wire 30 is hooked onto hook 18 on the proximal endof drill pin 12. By pulling on the drill pin, the graft-passing wire isdrawn through the femur until it is positioned with equal lengths ateither end protruding from the medial and lateral sides of the femoralshaft. Hemostats 74 are clipped onto the ends of the wire to preventthem from being pulled into the transverse femoral tunnel 70, as shownin FIG. 14.

Referring to FIGS. 13 and 14, once the graft-passing wire has been drawnthrough the femur, tunnel hook 2 is retracted from femoral socket 60 andtibial tunnel 56, pulling graft-passing wire 30 with it to form a loopthat protrudes from the entrance of tibial tunnel 56 on the anteriortibial cortex. The semitendinosus and gracilis tendons 76 are placedevenly over the wire loop, and the loop containing the tendons isretracted in the direction of arrow C back through the tibial tunnel andinto the femoral socket by pulling evenly on the medial and lateral endsof the graft-passing wire, as shown by arrows D and E, respectively.Twisting of the graft during insertion is avoided.

Referring to FIG. 15, once the tendons 76 have been drawn completelyinto femoral socket 60, implant 40 is inserted over the guide wire andadvanced by hand until the threaded section 44 contacts the femur. Animplant impactor 78 is chucked into driver/extractor 72 and placed overthe wire 30. The head of the implant 40 is engaged and a mallet is usedto drive the implant into the femur until a depth stop 82 on the driver78 contacts the cortical bone. Pulling on the tendons 76 is avoidedduring impaction of the implant 40.

The implant is advanced along the wire in the direction of arrow F. Theimplant passes under the loop formed in tendons 76, toward the medialside of the femur, to provide cross-pin support of tendons 76. Ifremoval of the implant should become necessary, reverse cutting threads44 facilitate removal by unscrewing the implant with a 3.5 mm hex headscrewdriver.

Referring to FIG. 16, the repair is completed by interference screw 84fixation of graft 76 in tibial tunnel 56. The femoral tunnel is narrowso that tendons 76 fit snugly within tibial tunnel 56 and femoral socket60, thus avoiding wiping of the tendons along the implant.

Although the present invention has been described in relation toparticular embodiments thereof, many other variations and modificationsand other uses will become apparent to those skilled in the art.Therefore, the present invention is to be limited not by the specificdisclosure herein, but only by the appended claims.

What is claimed is:
 1. A method of anterior cruciate reconstruction kneesurgery, comprising the steps of: forming a socket in a femur, thesocket having an entrance; forming a transverse hole in the femurextending completely across the femur, the transverse hole extendingthrough a first sidewall of the socket on a first side of the femur,intersecting the socket, and extending through an opposite sidewall ofthe femur on the opposite side of the socket; introducing a flexiblestrand into the knee, the flexible strand extending through thetransverse hole and into the socket through the first sidewall of thesocket, out through the socket entrance, and, after forming a loopoutside of the socket entrance, extending back into the socket entranceand out of the knee through the transverse hole in the opposite sidewallof the socket; engaging a graft with the loop of the strand extendingout of the socket entrance; and pulling the graft into the socket bypulling on opposite ends of the strand extending out of the transversehole on the opposite sides of the femur.
 2. The method of claim 1,further comprising the step of securing the graft in the socket using atransverse implant.
 3. The method of claim 2, wherein the implant iscannulated, the method further comprising the step of guiding theimplant using the strand.
 4. The method of claim 1, wherein the step offorming a socket comprises forming a socket that is closed at one end.5. A method of anterior cruciate reconstruction surgery of the knee,comprising the steps of: forming a socket in a femur, the socket havingan entrance; forming a transverse hole in the femur extending completelyacross the femur and intersecting the socket, the transverse holeextending from a first side of the femur on one side of the socket to anopposite side of the femur on the opposite side of the socket;positioning a flexible strand in the knee such that the flexible strandextends into the socket through the transverse hole on the first side ofthe femur, extends out through the socket entrance, and extends backinto the socket entrance and out of the transverse hole on the oppositeside of the femur; engaging a graft with a portion of the strandextending out of the socket entrance; and pulling the graft into thesocket by pulling evenly on opposite ends of the strand extending out ofthe transverse hole on the opposite sides of the femur.
 6. The method ofclaim 5, further comprising the step of securing the graft in the socketusing a transverse implant.
 7. The method of claim 6, wherein theimplant is cannulated, the method further comprising the step of guidingthe implant into the knee and under the graft using the strand.
 8. Themethod of claim 7, wherein the implant has a threaded back end, themethod further comprising the step of securing the implant in the kneeby engaging a wall of the hole with the threaded back end of theimplant.
 9. The method of claim 5, wherein the step of forming a socketcomprises forming a socket that is closed at one end.
 10. The method ofclaim 5, further comprising the portion of the strand extending out ofthe socket entrance forms a loop, and the graft is engaged in the loop.